If it is cold outside, let the wax harden and then peel it off. You might want to use a scraper.
If it is hot outside, or you if you have a garage: Outside, place brown paper bags over the waxed area, replacing each one as it becomes saturated. If you have a garage, you can do the same paper bag treatment, but to speed things up you can use an iron (the kind you use on clothing) to increase the heat. Place the brown paper bag over the area, cover that with an old terry cloth towel and then iron the area using the linen setting. Replace the bags as they become saturated.
Then use a soft rag to buff the window until no trace of wax remains.